consists of two or more rows of posts or piles. TheFigure 1-3.Typical pile bent.INTERMEDIATE SUPPORTSBents and piers provide support for the bridgesuperstructure at points other than the bank ends. A bentconsists of a single row of posts or piles, while a pierfollowing text discusses some of the different types ofbents and piers.The pile bent shown in figure 1-3 consists of thebent cap, which provides a bearing surface for the bridgestringers, and the piles, which transmit the load to thesoil. The support for the loads may be derived eitherfrom column action when the tip of the pile bears onfirm stratum, such as rock or hard clay, or from frictionbetween the pile and the soil into which it is driven. Inboth cases, earth pressure must provide some lateralsupport, but traverse bracing is often used to brace thebent laterally.A timber pile bent consists of a single row of pileswith a pile cap. It should be braced to the next bent orto an abutment to reduce the unbraced length and toprovide stability. This bent will support a combined spanlength of 50 feetThe trestle bent shown in figure 1-4 is similar to thepile bent except that the posts, taking the place of thepiles, transmit the load from the cap to the sill. The silltransmits the load to the footings, and the footingstransmit the load to the soil. Timber trestle bents arenormally constructed in dry, shallow gaps in which thesoil is firm. They are not suitable for use in soft soil orswift or deep streams. The bent can support a combinedspan length of up to 30 feet and can be 12 feet high.Figure 1-4.Timber trestle bent.1-3